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From: "Ahmed S. Darwish" <darwish.07@gmail.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>,
	Simon Horman <horms@verge.net.au>,
	Vivek Goyal <vgoyal@redhat.com>, Haren Myneni <hbabu@us.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>, X86-ML <x86@kernel.org>,
	KEXEC-ML <kexec@lists.infradead.org>,
	"H. Peter Anvin" <hpa@zytor.com>
Subject: Saveoops: Making Kexec purgatory position-independent?
Date: Sat, 26 Feb 2011 18:20:08 +0200	[thread overview]
Message-ID: <20110226162008.GA23879@laptop> (raw)

Hi,

I'm continuing work on 'Saveoops', saving both early and normal Linux
oops log to disk upon panic [*], using Kexec and bootloaders this time.

Purgatory, the transitional mini-kernel used by kexec, is a relocatable
ELF file. Userspace kexec-tools finds the final load address of such
code (by parsing /proc/iomem, etc) and then applies the relocations
itself before passing the now-ready executable image to kernel.

Since capturing early oopses is the major goal, doing such relocation
in userspace won't fit my purposes. Two options remain:
   - relocate purgatory entries in the kernel early boot path
   - or compile purgatory as position-independent, thus simplifying
     the kernel load logic

The former will add extra logic in a sensitive path (early boot), while
the latter will require changes inside the purgatory code itself,
especially i386 assembly files.

Any preferable option from our kexec and x86 maintainers?

thanks!

[*] http://news.gmane.org/find-root.php?message_id=<20110125134748.GA10051@laptop>
    http://news.gmane.org/find-root.php?message_id=<20110126124954.GC24527@laptop>

-- 
Darwish
http://darwish.07.googlepages.com

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http://lists.infradead.org/mailman/listinfo/kexec

             reply	other threads:[~2011-02-26 16:20 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-02-26 16:20 Ahmed S. Darwish [this message]
2011-02-26 21:38 ` Saveoops: Making Kexec purgatory position-independent? H. Peter Anvin
2011-02-27  0:57   ` Eric W. Biederman
2011-02-27  1:15     ` H. Peter Anvin
2011-02-27 13:24     ` Ahmed S. Darwish
2011-02-27 14:16       ` Vivek Goyal
2011-02-27 15:43         ` Ahmed S. Darwish
2011-02-27 18:32       ` Eric W. Biederman
2011-02-28  1:38     ` Simon Horman
2011-02-28  1:39     ` H. Peter Anvin

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